Ecological functioning of bacterial chitinases in soil

Chitin is the second most abundant polymer in nature. In aquatic ecosystems, chitin is mainly present as part of the exoskeleton of arthropods; in soil, chitin is mainly present as component of fungal cell walls. The main enzymes involved in the breakdown of chitin are chitinases. Chitinases are produced by both fungi and bacteria. Chitinases of soil-borne bacteria can decompose chitin of dead fungal hyphae and other resources, but they may also play a role in antagonistic activities against fungi by destroying the chitin in the fungal cell walls. In the research described in this thesis, I tested the hypothesis that bacterial chitinases may perform different functions in different environments and under different circumstances, while the genetic composition and function of bacterial chitinases vary between different habitats. The results obtained in this study have contributed to a better understanding of the ecological functions of bacterial chitinases. New insights in the composition of the bacterial chitinolytic system and the importance of its components were obtained. The potential ecological functions of the bacterial chitinase complex were explored and the role of chitinases in bacteria-fungi interactions, which are vital to the functioning of terrestrial ecosystems, was revealed further.